The fact that the Al Qaeda leader was caught in the heart of the nation may add to the questions in Washington over how much Pakistan's security forces knew about his whereabouts.

Reporting from Islamabad, Pakistan – — The fact that Osama bin Laden was killed not in the tribal badlands of northwestern Pakistan but in a small city just north of the capital is likely to raise new suspicions in Washington about how much the country's security establishment knew of his whereabouts — and whether elements of it assisted him.

FOR THE RECORD Pakistan and Bin Laden: An article in the May 2 Section A about Pakistan and the death of Osama bin Laden said that Khalid Shaikh Mohammed, principal architect of the Sept. 11 attacks, was captured in 2003 in Karachi, Pakistan. He was captured in Rawalpindi, Pakistan.For many years, the hunt for Bin Laden focused on the rugged tribal areas along the Afghan border. Instead, he was killed in the city of Abbottabad, in a neighborhood near the Pakistan Military Academy, the training center that has produced many of the country's powerful military leaders.

That Bin Laden was caught in the heart of the Pakistani state may deepen the mistrust between the U.S. and its nominal anti-terrorist ally, which is the recipient of billions of dollars in U.S. military aid.

Officials in Washington have long accused the Pakistani government and its security bodies of providing sanctuary and other means of support to militant groups that were closely allied with Al Qaeda and helped the terrorist organization hide and operate there.

In July, Secretary of State Hillary Rodham Clinton bluntly accused the Pakistani government of less than full cooperation in the hunt for Bin Laden.

Clinton did not charge that top government officials were protecting the Al Qaeda leader, but instead said she believed that elements of the bureaucracy had to know where he was hiding.

A senior U.S. official who briefed reporters at the White House late Sunday said no Pakistani forces were involved in the operation to kill Bin Laden and that Pakistan was not told of the mission beforehand.

However, agents with Pakistan's primary intelligence agency were quick to claim some of the credit. A source in the Inter-Services Intelligence agency, or ISI, described the mission in Abbottabad, about 35 miles north of Islamabad, as a joint operation.

The source said the team stormed the compound where Bin Laden was staying shortly after midnight Monday, engaged in a firefight with Al Qaeda gunmen, and killed the Al Qaeda leader.

Some Pakistani officials say Bin Laden's death is evidence that the two countries can cooperate despite the mistrust that has troubled their relationship.

Until recently Pakistan had tacitly approved the campaign of drone missile strikes focused on Al Qaeda and Taliban figures in the tribal areas.

Though Pakistan's cooperation with the U.S. drone program had been recently halted, many of the drone strikes were carried out with the assistance of Pakistani intelligence operatives who assisted the targeting of militants.

Pakistan can also claim its own successes against Al Qaeda, the most prominent of which was the 2003 arrest of Khalid Shaikh Mohammed, the principal architect of the Sept. 11 attacks, who was captured in Pakistan's largest city, Karachi, by Pakistani intelligence agents.

The two sides also have cooperated in rounding up senior Taliban figures.

Pakistani security forces detained Mullah Abdul Ghani Baradar, the Afghan Taliban's second-in-command, in Karachi early last year on the basis of intelligence provided by the United States.

Although Al Qaeda had its sympathizers in Pakistan's volatile northwest, Bin Laden's death is likely to be celebrated across much of the country.

"Yes, our relationship was strained," the Pakistani intelligence source said. "But this operation [in Abbottabad] is testimony to the fact that we continue to work together for the greater good."

The CIA and the ISI have been at odds with each other since the arrest of Raymond Davis, the American who shot to death two Pakistani men who he said were trying to rob him in Lahore on Jan. 27.

Angered by the revelation that Davis was a CIA contractor, the ISI put joint operations with the CIA on hold and later demanded a sharp reduction in the number of the American intelligence agency's operatives based in Pakistan, as well as detailed information on the assignments of its remaining personnel. Photos: Reactions to Osama bin Laden death